Ok heres the skinny. The difference between a 4W prop and a 6 prop is obviously pitch and width you can prop a saito 100 with a variety of props in their range say the smallest prop is a 14X6 thats listed just as an example. In writing a 14X4W equates to a 14x6 in loading terms. They will swing the same rpm's ( or close) but your difference is power and torque vs. Speed. If you are finding that your plane is taking too long to spool up doesnt mean you need to ditch the W prop and go to a 6. There are other options, a std 4 pitch without the W or even 1" dia smaller say 13x4W. All of the manufactures lited props can be thrown out the window when it comes to 3D there is a different approach to it. Some people perfer a 6 or 8 to a 4 or 4W but thats because they want that slower response time in power. But the purpose of a 4 or 4W prop is to slow the plane down. 3D planes were not meant to go a million miles an hour but more like being able to pull a house, which is what a 4W prop does vs a 6 or 8 and up. In wingmans case he is going for a 13X8 from a 14X4W personally it may give you a slightly higer RPM but it will not pull harder than the 14x4W. you will gain speed no doubt but not the power you are looking for. You will see that your pull out in a hover will still be lacking. Try a 13X4W. point is you dont want to get away from that power prop and rule of thumb is low pitch large diameter for power. Once you get it narrowed to the approx lenght and pitch size its a delicate balance in there to get it to your liking. Then there is always a curve point you can dial into your Computer radio if you have one that can. It can broaden or narrow the throttle band to help with your spool time and and or thottle response.